1. Technical Field
The present invention relates to structures of emissive devices including various emissive materials such as organic electroluminescent materials.
2. Related Art
Active matrix emissive devices including switching elements, such as transistors, for controlling light emission from luminescent layers have been proposed. For example, JP A-2002-318556 discloses such an emissive device including the switching element disposed on a surface of a substrate, an insulating layer covering the switching element, a first electrode and a second electrode that are disposed on the surface of the insulating layer, and the luminescent layer disposed between the electrodes. The first electrode is electrically connected to the electrode (a drain electrode or a source electrode) of the switching element via a contact hole disposed in the insulating layer.
However, in this structure, external light, such as sunlight and light from a luminaire, passes through the contact hole in the insulating layer, reaches the electrode of the switching element, is reflected from the surface, and emerges from a viewing side, in some cases. The light reflected from the surface is referred to as “undesirable reflection”, hereinafter. The undesired reflection has characteristics, such as light intensity and spectral characteristics, different from those of light from the luminescent layer, thus causing the nonuniformity of the quantity of light, i.e., nonuniformity of luminance, in the plane of the emissive device.
Furthermore, for example, in a structure in which a luminescent layer is formed not only on an insulating layer but also inside a contact hole, light (hereinafter, referred to as “undesirable light”) is also emitted from the portion of the luminescent layer disposed along the inner surface of the contact hole. However, the portion of the luminescent layer disposed on the surface of the insulating layer has a thickness different from that of the portion of the luminescent layer disposed inside the contact hole; hence, light emitted from the former portion has the quantity of light and spectral characteristics different from those of the light emitted from the latter portion. Therefore, the undesirable light in the structure can also cause the nonuniformity (unevenness) of the quantity of light in the plane of the emissive device.